1. Field of the Invention
The present invention relates to a liquid crystal display device in which a wide viewing angle is controlled by controlling a longitudinal electric field, and a method of driving the same.
2. Discussion of the Related Art
A liquid crystal display device, particularly, a liquid crystal display device using a thin film transistor (TFT) is widely used, for example, in a mobile communication telephone and a TV.
Among the above-mentioned displays, there is required a personal display in which displayed content can be seen by a user of the personal display, but is not seen to another person who views the personal display in the horizontal direction.
Particularly, the displayed content may be shared with several people sometimes, but preferably, may be used personally.
In the past, in order to improve the viewing angle characteristic, in-plane switching (IPS) technology and fringe field switching (FFS) technology have been proposed. The IPS and FFS technologies, are manufactured in commercial scale (for example, See Japanese Unexamined Patent Application Publication Nos. 2003-75819 and Hei 5-108023).
According to the IPS technology, electrodes are formed on a same substrate and an electric field is applied between the electrodes to activate a liquid crystal response to display gray scale. Because the electrodes are formed on the same substrate, a parallel component of the electric field is strong, and consequently, characteristics of a wide viewing angle can be obtained.
According to the FFS technology, an insulator film is put on a same substrate to form a first electrode and a second electrode and an electric field is applied between the electrodes such that the liquid crystals respond to display gray scale. Because the electrodes are formed on the same substrate, the parallel component of the electric field is strong and consequently, a wide viewing angle can be obtained.
However, according to the related art, even though the characteristics related to the viewing angle are improved, there is a limit that the viewing angle cannot be adjusted to be narrow or wide in order to maintain the security of displayed information.